• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.95-99
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• 2008

Various etching methods of optical fiber and formation of metal nano particles on the optical fiber have been proposed for fabrication of fiber optic localized surface plasmon resonance (FO LSPR) biosensors. Different types of etched optical fiber are possible by removing the cladding of optical fiber using HF (hydrofluoric acid) solution and BHF (buffered hydrofluoric acid) solution, which results in improved surface roughness when BHF solution is used. Localized surface plasmon can be formed and measured by formation of silver and gold nano particles on the etched optical fiber. The characteristics of the etched optical fiber and metal nano particles on the etched surface of the optical fiber play a key role in dictating the sensitivity of the LSPR sensors, so that the proposed results can be expected to be applied for related research on fiber optic based biosensors.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1349-1354
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• 2003

Ultrasonic Machining process is an efficient and economical means of precision machining on glass and ceramic materials. However, the mechanics of the process with respect to crack initiation and propagation, and stress development in the ceramic workpiece subsurface are still not well understood. In this research, we investigate the basic mechanism of chemical assisted ultrasonic machining(CUSM) of glass through the experimental approach. For the purpose of this study, we designed and fabricated the desktop micro ultrasonic machine. The feed is controlled precisely by using the constant load control system. During the machining experiment, the effects of HF(hydrofluoric acid) characteristics and machining condition on the surface roughness and the material removal rate are measured and compared.

• Current Photovoltaic Research
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• v.5 no.3
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• pp.75-82
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• 2017

High efficiency thin film solar cells require an absorber layer with high absorption and low defect, a transparent conductive oxide (TCO) film with high transmittance of over 80% and a high conductivity. Furthermore, light can be captured through the glass substrate and sent to the light absorbing layer to improve the efficiency. In this paper, morphology formation on the surface of glass substrate was investigated by using HF, mainly classified as random etching and periodic etching. We discussed about the etch mechanism, etch rate and hard mask materials, and periodic light trapping structure.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.737-740
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• 1997

The influence of cyclic treatments with H2O2/DIW (1 : 10) and HF/DIW (1 : 100) on the roughness of silicon surface in the wet chemical processing was investigated by atomic force microscopy (AFM). During the step of the SC-1 cleaning, there is a large increase in roughness on the silicon surface which will result in the poor gate oxide breakdown properties. The roughness of the silicon wafer after the SC-1 cleaning step was reduced by cyclic treatments of hydrogen peroxide solution and hydrofluoric acid solution instead of HF-only cleaning. AFM images after each step clearly illustrated that the average roughness of silicon surface after three times treatments with H2O2 and HF solutions was reduced by 10 times compared with that after the SC-1 cleaning step.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.111-114
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• 1998

Lithium Niobate {{{{ { LiNbO}_{ 3} }}}} single crystals grown by Czichralski method at the congruent composition, have ferroelectric microdomains. These microdomins were investigated by chemical etching with hydrofluoric acid (HF) AND NITRIC ACID ({{{{ { HNO}_{3 } }}}}), and by us ing optical microscopy, scanning electron microscopy and atomic force microscopy

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.557-560
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• 2009

In this study, a new wet etching method and the solution for thinning the glass with the thickness below $100{\mu}m$ were investigated. For the preparation of etching solution with low hydrofluoric acid, it was effective to use $NH_4F$ or $NH_4HF_2$ as a main ingredient with the addition of sulfuric acid or nitric acid. Influence of the composition of mixed acid solution and the temperature on the etching rate was investigated. The addition of anionic surfactant provides the function to prevent the adhesion of sludge generated by the etching reaction. A new wet etching pilot device equipped with streaming generation parts was used to test etching of commercial non-alkali glass and soda lime glass. The non-alkali glass with the thickness of 640 ${\mu}m$ and soda lime glass with the thickness of $500{\mu}m$ were etched to $45{\mu}m$ and $100{\mu}m$, respectively, by using the pilot device. After the etching by pilot device, the roughness degree of the glass surface was maintained at $0.01{\sim}0.02{\mu}m$.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.144-155
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• 1997

This study evaluated shear bond strength between porcelain and resin cement according to various surface treatments of porcelain, and surface condition of debonded porcelain. 50 porcelain specimens(Celay block A2M7) and composite resin specimens(Clearfil Photo-Bright) were prepared, and divided into 5 experimental groups according to the treatment method of porcelain surface. 5 experimental groups by surface treatments were as follows; CONTROL Group : No surface treatment was done on the surface of porcelains. SAND Group : The surface of porcelains were sandblasted with $50{\mu}m$ aluminum oxide for 5 seconds. HF Group: The surface of porcelains were etched with 8% Hydrofluoric acid for 4 minutes. SIL Group: The surface of porcelains were coated with silane coupling agent and heated at $100^{\circ}C$ for 5 minutes. SAND+HF+SIL Group : The surface of porcelains were sandblasted with $50{\mu}m$ aluminum oxide for 5 seconds and etched with 8% Hydrofluoric acid for 4 minutes, and coated with silane coupling agent and heated at $100^{\circ}C$ for 5 minutes. After surface treatments on the prepared porcelain surface two pastes of Panavia 21$^{(R)}$ were mixed, they were applied between composite resin block and porcelain surface, and then excessive resin cements were removed, and its margin was surrounded with Oxyguard II. All specimens were stored for 24 hours in water at $37^{\circ}C$ and tested with Instron testing machine between porcelains and resin cements, and debonded porcelain surfaces were observed under Scanning Electon Microscope(Hitachi S-2300) at 20kvp. The values from each group were compared statistically by Student's t-test. The obtained results were as follows; 1. The shear bond strength without surface treatment of porcelain was the lowest among all experimental groups(p<0.05). 2. The detached porcelain surface with sandblasting alone had more remarkable cracks than with only Hydrofluoric Acid or Silane coupling 2gent, but showed the lowest value of shear bond strength among surface treated groups(p<0.05), 3. When porcelain surface was treated by hydrofluoric acid, it affected shear bond strength more than silane coupling agent, but there were no significant statistical differences(p>0.05). 4. When three methods were combined to increase shear bond strength between porcelains and resin cements, its value was the highest than the others(p<0.05). 5. In Scannig Electron Micrograph of detached porcelain surface with no treatment, the sample revealed adhesive failure between the porcelain and resin cement whereas detached porcelain surface with combination of three method cohesive failure on the porcelain.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.99-103
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• 2008

To improve efficiency of solar cells, it is important to make a light trapping structure to reduce surface reflectance for increasing absorption of sun light within the solar cells. One of the promising methods that can reduce surface reflectance is isotropic texturing with acid solution based on hydrofluoric acid(HF), nitric acid($HNO_3$), and organic additives. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its different grain orientation. Isotropic texturing with acid solution can uniformly etch multicrystalline silicon wafers unrelated with grain orientation, so we can get low surface reflectance. In this paper, the acid texturing solution is made up of only HF and $HNO_3$ for easy controlling the concentration and low cost compared to acid solution with organic additives. $HNO_3$ concentration and dipping time were varied to find the condition of minimum surface reflectance. Textured surfaces were observed Scanning Electron Microscope(SEM) and surface reflectance were measured. The best result of arithmetic mean(wavelength from 400 nm to 1000 nm) reflectance with acid texturing is 4.64 % less than alkali texturing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.16-17
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• 2007

To improve efficiency of solar cells, it is important to make a light trapping structure to reduce surface reflectance for increasing absorption of sun light within the solar cells. One of the promising methods that can reduce surface reflectance is isotropic texturing with acid solution based on hydrofluoric acid(HF), nitric acid($HNO_3$), and organic additives. Anisotropic texturing with alkali solution is not suitable for multicrystalline silicon wafers because of its different grain orientation. Isotropic texturing with acid solution can uniformly etch multicrystalline silicon wafers unrelated with grain orientation, so we can get low surface reflectance. In this paper, the acid texturing solution is made up of only HF and $HNO_3$ for easy controling the concentration and low cost compared to acid solution with organic additives. $HNO_3$ concentration and dipping time were varied to find the condition of minimum surface reflectance. Textured surfaces were observed Scanning Electron Microscope(SEM) and surface reflectance were measured. The best result of arithmetic mean(wavelength from 400nm to 1000nm) reflectance with acid texturing is 4.64% less than alkali texturing.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.629-638
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• 2016

In this study, the effect of inorganic constituents on the physicochemical properties of pyrolytic products produced from empty fruit bunch (EFB) by fast pyrolysis were investigated. Inorganic constituents were removed from the EFB by means of washing treatment with hydrofluoric acid (HF) and distilled water (D.I water). Ash content decreased from 6.2 wt% (EFB) to 2.4 wt% (HF-EFB) and 3.5 wt% (D.I-EFB), respectively. As a result of the inorganic component, a quantity of potassium in EFB has showed the highest removal efficiency in both HF and D.I water (HF: 80.3%, D.I water: 72.8%). Fast pyrolysis was performed with demineralized EFB in the fluidized bed reactor under the temperature of $500^{\circ}C$ at the residence time of 1.3 sec. The yield of bio-oil was determined to 57.3 wt% for HF-EFB and 52.1 wt% for D.I-EFB, respectively. Biochar yield decreased whereas yield of non-condensable gas increased with decreasing inorganic content of EFB. Water content decreased from 26.9% (EFB) to 9.9% (HF-EFB) and viscosity increased from 16.1 cSt (EFB) to 334 cSt (HF-EFB).